If it's specified to have a physical implementation, I think infinite-computation AIXI could actually get around dualism by predicting the behavior of its own physical implementation. That is, it computes outcomes as if the output channel (or similar complete output-determiner) is manipulated magically at the next time step, but it computes them using a causal model that has the the physical implementation still working into the future.

So it wouldn't drop a rock on its head, because even though it thinks it could send the command magically, it can correctly predict the subsequent, causal behavior of the output channel, i.e. silence after getting smooshed by a rock.

This behavior actually does require a non-limit infinity, since the amount of simulation required always grows faster than the simulating power. But I think you can pull it off with approximation schemes - certainly it works in the case of replacing exact simulation of future self-behavior with heuristics like "always silent if rock dropped on head" :D